I get food stains all the time. It's worse when it's chilli oil, it never comes off with regular washing. What I do is use dish washing liquid and it comes off after a while. It helps if you immediately wet the spot that's stained, sort of dilute it so that cleaning is easier later. Whatever you do, don't leave it overnight to wash, do it immediately when you get back. And don't iron the stain, it will be permanent once the hot iron goes over it. I hate it when I have to go for hot pot wearing white shirts! Not matter how I try to be careful, I come back with spots on it and it's a bitch cleaning white shirts, especially cotton ones.

I would blame the washing powder rather than the washing machine. You have strong washing powder for hard-to-remove stains, like White Cat in every supermarket I've been in China.

My mum said:

'soak bleach over stains on whites, and wash it in the machine. You shouldn't mix colored laundry with whites, because you'll have discoloring spots on colored clothes (like me), when machine will stop.

My mum also use technique called 'spots hand wash', before machine wash, what I never do.

I use liquid detergent, and soak dirty spots on colored or white laundry with pure, not diluted detergent, and leave it overnight. Then, I add a bit more detergent to the machine than regular not that dirty clothes, and start machine. Spots are mostly gone.

I also use the most expensive detergent, 'cause I'm convinced, price of the detergent determine quality of the soap.

My wife literally just complained about this to me. Like what was mentioned above I said it was the detergent.

The monkey is right. And a thing most Chinese seems to be unaware of (at least the women peddling laundry products in supermarkets) is that there is a difference between washing powder for cold water and for warm water. You gotta use the right thing for your washing machine. 

I'd always go for a front loading washing machine that can do warm washing. It's just more hygienic to do some washes at 60C (or 90C if you are feeling like wasting power) 

hot water washing machines, guess i still live in the sticks, never seen one in china.

It depends also on the food stain and the material.

All should be dealt with as soon as possible and individually.

But i know that chances are this is not always a realistic option.

i always soak stains in water with 20 percent white vinegar, something my late grandmother told me, but im not sure of the quality of white vinegar in china, dont know how easy it is to screw up vinegar, it does clean the hot water cooker i have for coffee, the water from the tap leaves a nice yellow covering all over the stainless steel every week but vinegar cleans it up, no wonder the japanese drink vinegar and water to clean out their body, perhaps im missing something.